Sea stars in the last 3 years have drastically declined along the West Coast of the US. The reason for this multi-species decline has been linked to an epizootic called Sea Star Wasting Disease (SSWD) and is the largest marine disease event ever recorded. This disease is as morbid as it sounds; anatomically the stars appear to lose tutor in their extremities and their arms literally tear apart from the body of the star.
Last year SSWD received lots of media attention, but it is still on-going with further mortality noted this summer. More work is needed to understand why this event is occurring and understanding how this disease affects the stars is one of the first things to understand. Our paper, “Up in Arms: Immune and Nervous System Response to Sea Star Wasting Disease” released today, in PLOS ONE examines the physiological response to SSWD inoculum. In other words, fluid from diseased “wasted” stars was injected into seemingly healthy sea stars to assess the response to the disease. Once the signs of SSWD were apparent (e.g. twisting and apparent lesions), samples were sequenced to compare the responses of individual stars.
By comparing the transcriptomic profile of infected stars to non-infected, we were able to note which genes and pathways were differentially expressed as a response to the treatment. Genes involved with nervous system and/or neural networks were strongly expressed in infected stars, supporting the signs of SSWD (i.e. abnormal twisting of arms). Many of the genes were immune-related genes, which may be intuitive, however the immune system of many invertebrates is largely unknown and poorly understood, so this provides more insight into the immune response of sea stars, echinoderms, or even more broadly invertebrates.
This paper is a product of a course offered last summer at the University of Washington’s Friday Harbor Laboratories (FHL). Students and researchers involved with the Ecology of Infectious Marine Diseases course analyzed the data and comprised the manuscript. Financial support from both FHL and the NSF-funded Research Coordination Network for the Ecology of Marine Infectious Diseases made this work possible.
For more information about the paper click the link below:
For further entertainment enjoy our SSWD-adaptation of ‘Life Aquatic’: